Not applicable
Not applicable
This invention relates to an audio signal control system and to a method of operating an audio signal control system.
When an audio engineer mixes several audio tracks together to form a final production version, the level of each channel for each track of the mix is varied throughout the production on a digital mixing console. Thus an audio signal is recorded via plural channels onto several audio tracks and each one of the audio tracks may be subsequently modified by an audio engineer. The modified audio signal is stored so that the final production audio signal is usually a result of several prior versions of the audio signal having been modified. In the digital mixing console each of the audio signal levels is defined by plural sequences of numeric values generated using a fader control coupled to an analog to digital converter (ADC).
The numeric values are stored and the levels are subsequently used by a digital signal processor (DSP) in conjunction with the associated digital audio samples in a mixing calculation, the result of which is converted to an analog signal in a digital to analog converter (DAC) and subsequently aurally played on a speaker.
Known audio production equipment may record the sequences of numeric values generated from the fader controls and store the sequences in memory, such as a disk drive.
When replaying the audio signal, the fader controls are moved approximately in synchronism in dependence upon the sequences stored in memory so that the fader controls mimic their original positions. When an audio engineer wishes to modify a track of the audio signal, the appropriate fader control is moved to a new position and when the audio engineer is satisfied that the new position is correct then the new sequence of numeric values for the fader control is stored.
In the known equipment, in the step of storing the new version of the fader control numeric position, the previous version is overwritten.
The present invention seeks to provide an apparatus and a method in which current and previous versions of the numeric values generated by the fader control are stored so that an audio engineer may revert back to a previous version, if desired.
According to a first aspect of this invention there is provided an audio signal control system including means for determining plural sequences of a control parameter for generating an audio signal to produce a first version, means for storing said plural sequences of said control parameter, means for modifying said audio signal, and means for determining and storing only the sequence or sequences of said control parameter that were modified in modifying said audio signal, and means for reassembling said control parameter from said sequences derived from various versions of said sequence or sequences.
In a preferred embodiment, the means for modifying said audio signal produces a modified sequence or sequences of said control parameter to produce a further version of said sequence or sequences and means are provided for assembling the originally stored version of sequences altered by said modified sequence or sequences, whereby said original and said further version are stored by said storing means.
Preferably said means for storing is arranged to store N versions of said sequences and conveniently N may be equal to 10.
In a feature of this invention there is provided an audio signal control system including means for generating an audio signal connected to means for storing a control parameter associated with said audio signal, means for modifying said stored audio signal and at least a portion of said control parameter, said control parameter being divided into plural sequences and said portion being a sequence or sequences of said control parameter, means for storing at least one sequence of said control parameter that is modified by said modifing means whereby said means for storing stores said original control parameter and said modified control parameter.
Preferably the control parameter is produced by a position control means such as a slider control or a rotary control.
Advantageously means are provided for replaying said stored audio signal in dependence upon a desired serial sequence of said control parameter stored in different versions thereof, and said means may conveniently comprise a digital signal processor receiving signals from said storage means and outputting signals via a digital to analog converter to an audio speaker.
According to a further aspect of this invention there is provided an audio signal control method including the steps of determining plural sequences of a control parameter for generating an audio signal to produce a first version, storing said plural sequences of said control parameter as said first version, and when modifying said audio signal, determining and storing only the sequence or sequences that were modified to produce a second version whereby both said first version and said second version are stored for subsequent recall, and assembling said control parameter from said sequences derived from said first version and said second version for utilisation.
In a currently preferred embodiment, the modified sequence or sequences produce a second version comprising said first version of sequences altered by said modified sequence or sequences whereby both said first version and said second version formed by said first version modified by said altered sequence or sequences are stored in their entirety. In another embodiment the modified sequence or sequences is stored by storing the change in parameter of the modified sequence or sequences rather than the actual modified sequence or sequences. In a further embodiment, only the modified sequence is stored with an appropriate address.
Preferably N versions may be stored and conveniently N may be equal to 10.
Advantageously each said sequence has a predetermined length, of for example 4096 bytes.
Preferably each sequence comprises parametric control data and a unique identifier code, which identifier code may be for example a numerical code. A version typically may comprise plural sequences plus associated identifier codes.
Conveniently, a predetermined sampling rate of for example 50 Hz is used to determine the location of the sequence or sequences that are modified in a series string of such sequences.
It will be understood from the above that the system and method of this invention in the preferred embodiment stores control parameters associated with an audio signal in a sequence of numbers so that a version of said control parameters may be stored. When the control parameter is changed to change the audio signal, the particular number of the sequence or sequences that is modified replaces the originally stored sequence (version) so that both original and modified versions of sequences are stored for subsequent use.